Ball bats made out of glued laminations are known, such as that disclosed by U.S. Pat. No. 5,490,669. Such bats provide a number of advantages, including particularly increased strength resulting in part from the 180 degree rotation of adjacent plies. Such rotation causes the wood grain in adjacent plies to be substantially mirror images. As a result, the wood throughout the bat is more uniform, thereby decreasing the likelihood of a weak spot, which tends to result in a stronger bat.
Additionally, as a result of the cuts made to separate the plies, the "inside" of the wood is revealed. This can result in the observation of weak spots, allowing replacement with stronger wood. However, known laminated bats have not addressed the issue of nondestructive testing of each of the lamina used to make the bat As a result, the use of substandard lamina is possible. As a result, it is the case that known laminated bats are constructed of individual lamina arranged in locations within the bat that have stress levels that are incompatible with that particular lamina's strength level.
As seen above, the use of glued lamina in bat construction generally results in a stronger bat. However, since known laminated bats have used lamina having a uniform thickness, the resulting increase in strength is uniform throughout the bat, rather than being particularly directed to those areas of the bat that are more likely to break. This is because the specific area of breakage in most bats is an area generally located between the ball player's grip and the impact location of the ball, i.e. in a region between the handle and barrel. This implies that to decrease the likelihood of a bat breaking, certain "weak-link" areas need to be stronger, while other areas of existing bats are already unlikely to break Known laminated bats have not fully addressed the issues of selectively strengthening the weaker areas of a bat.